The opposition party leader is an Amnesty International prisoner of conscience, serving a life sentence in Kaliti prison in Addis Ababa. A single mother and former judge, she was among dozens arrested after the disputed 2005 elections, freed, and then re-arrested for saying her release had been due to opposition pressure on the government rather than a request by her for pardon.

Birtukan and others arrested in 2005 were pardoned after spending nearly two years in jail. In November 2008 she spoke at a public meeting in Sweden about her pardon, attributing her release and that of others to political negotiations between the opposition and the government rather than an official request made through legal channels.

While people who were in jail with her the first time say this reflected the truth, the government said it equated to denying asking for a pardon. When she returned to Ethiopia, authorities asked her to retract her statement, failing which she would be re-arrested. She refused and was re-arrested in December 2008, when the ministry of justice revoked her pardon and re-imposed her life sentence.

Since a court ruling on a complaint she filed against the prison, Birtukan - the only female leader of a main opposition party in Africa - has been allowed more regular visits from her immediate family, including her mother and her five-year-old daughter. However, she has reportedly had only intermittent access to legal representation.

Birtukan's imprisonment has garnered increasing public attention. Her supporters are planning a run for her in Turbingen, Germany on 19 September.

In its annual report on human rights around the world, the US state department's section on Ethiopia said: "Human rights abuses reported during the year included unlawful killings, torture, beating, abuse and mistreatment of detainees and opposition supporters by security forces, often acting with evident impunity; poor prison conditions; arbitrary arrest and detention, particularly of suspected sympathisers or members of opposition or insurgent groups..."

Opposition parties and human rights groups say Birtukan's case is stark evidence of the authoritarian tendencies of Meles Zenawi, the prime minister, a major recipient of western aid.

• This article was amended on 9 September 2010. The original referred to "Mideksa" on second reference instead of Birtukan. This has been corrected.